From abf5ab340ed76792214ae80c62df7abe0ad1b8a8 Mon Sep 17 00:00:00 2001
From: Matthew Holt <mholt@users.noreply.github.com>
Date: Tue, 15 Oct 2019 14:07:10 -0600
Subject: [PATCH] caddyhttp: Improve ResponseRecorder to buffer headers
---
modules/caddyhttp/caddyhttp.go | 13 +++
modules/caddyhttp/httpcache/httpcache.go | 5 +-
modules/caddyhttp/markdown/markdown.go | 6 +-
modules/caddyhttp/responsewriter.go | 119 ++++++++++++++++------
modules/caddyhttp/templates/templates.go | 18 ++--
modules/caddyhttp/templates/tplcontext.go | 2 +-
6 files changed, 116 insertions(+), 47 deletions(-)
diff --git a/modules/caddyhttp/caddyhttp.go b/modules/caddyhttp/caddyhttp.go
index 5631b300b..29a5ab071 100644
--- a/modules/caddyhttp/caddyhttp.go
+++ b/modules/caddyhttp/caddyhttp.go
@@ -593,6 +593,19 @@ func (ws WeakString) String() string {
return string(ws)
}
+// CopyHeader copies HTTP headers by completely
+// replacing dest with src. (This allows deletions
+// to be propagated, assuming src started as a
+// consistent copy of dest.)
+func CopyHeader(dest, src http.Header) {
+ for field := range dest {
+ delete(dest, field)
+ }
+ for field, val := range src {
+ dest[field] = val
+ }
+}
+
// StatusCodeMatches returns true if a real HTTP status code matches
// the configured status code, which may be either a real HTTP status
// code or an integer representing a class of codes (e.g. 4 for all
diff --git a/modules/caddyhttp/httpcache/httpcache.go b/modules/caddyhttp/httpcache/httpcache.go
index 1b2cfd2e9..0b49c7ee0 100644
--- a/modules/caddyhttp/httpcache/httpcache.go
+++ b/modules/caddyhttp/httpcache/httpcache.go
@@ -130,8 +130,7 @@ func (c *Cache) getter(ctx groupcache.Context, key string, dest groupcache.Sink)
// we need to record the response if we are to cache it; only cache if
// request is successful (TODO: there's probably much more nuance needed here)
- var rr caddyhttp.ResponseRecorder
- rr = caddyhttp.NewResponseRecorder(combo.rw, buf, func(status int) bool {
+ rr := caddyhttp.NewResponseRecorder(combo.rw, buf, func(status int, header http.Header) bool {
shouldBuf := status < 300
if shouldBuf {
@@ -141,7 +140,7 @@ func (c *Cache) getter(ctx groupcache.Context, key string, dest groupcache.Sink)
// the rest will be the body, which will be written
// implicitly for us by the recorder
err := gob.NewEncoder(buf).Encode(headerAndStatus{
- Header: rr.Header(),
+ Header: header,
Status: status,
})
if err != nil {
diff --git a/modules/caddyhttp/markdown/markdown.go b/modules/caddyhttp/markdown/markdown.go
index 122aad6e4..5ff18b88e 100644
--- a/modules/caddyhttp/markdown/markdown.go
+++ b/modules/caddyhttp/markdown/markdown.go
@@ -48,8 +48,8 @@ func (m Markdown) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyht
buf.Reset()
defer bufPool.Put(buf)
- shouldBuf := func(status int) bool {
- return strings.HasPrefix(w.Header().Get("Content-Type"), "text/")
+ shouldBuf := func(status int, header http.Header) bool {
+ return strings.HasPrefix(header.Get("Content-Type"), "text/")
}
rec := caddyhttp.NewResponseRecorder(w, buf, shouldBuf)
@@ -62,6 +62,8 @@ func (m Markdown) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyht
return nil
}
+ caddyhttp.CopyHeader(w.Header(), rec.Header())
+
output := blackfriday.Run(buf.Bytes())
w.Header().Set("Content-Length", strconv.Itoa(len(output)))
diff --git a/modules/caddyhttp/responsewriter.go b/modules/caddyhttp/responsewriter.go
index 344298f2f..5beb40ea3 100644
--- a/modules/caddyhttp/responsewriter.go
+++ b/modules/caddyhttp/responsewriter.go
@@ -18,6 +18,7 @@ import (
"bufio"
"bytes"
"fmt"
+ "io"
"net"
"net/http"
)
@@ -78,52 +79,89 @@ type responseRecorder struct {
wroteHeader bool
statusCode int
buf *bytes.Buffer
- shouldBuffer func(status int) bool
+ shouldBuffer ShouldBufferFunc
stream bool
size int
+ header http.Header
}
// NewResponseRecorder returns a new ResponseRecorder that can be
-// used instead of a real http.ResponseWriter. The recorder is useful
-// for middlewares which need to buffer a responder's response and
-// process it in its entirety before actually allowing the response to
-// be written. Of course, this has a performance overhead, but
-// sometimes there is no way to avoid buffering the whole response.
-// Still, if at all practical, middlewares should strive to stream
+// used instead of a standard http.ResponseWriter. The recorder is
+// useful for middlewares which need to buffer a response and
+// potentially process its entire body before actually writing the
+// response to the underlying writer. Of course, buffering the entire
+// body has a memory overhead, but sometimes there is no way to avoid
+// buffering the whole response, hence the existence of this type.
+// Still, if at all practical, handlers should strive to stream
// responses by wrapping Write and WriteHeader methods instead of
// buffering whole response bodies.
//
-// Recorders optionally buffer the response. When the headers are
-// to be written, shouldBuffer will be called with the status
-// code that is being written. The rest of the headers can be read
-// from w.Header(). If shouldBuffer returns true, the response
-// will be buffered. You can know the response was buffered if
-// the Buffered() method returns true. If the response was not
-// buffered, Buffered() will return false and that means the
-// response bypassed the recorder and was written directly to the
-// underlying writer. If shouldBuffer is nil, the response will
-// never be buffered (it will always be streamed directly), and
-// buf can also safely be nil.
+// Buffering is actually optional. The shouldBuffer function will
+// be called just before the headers are written. If it returns
+// true, the headers and body will be buffered by this recorder
+// and not written to the underlying writer; if false, the headers
+// will be written immediately and the body will be streamed out
+// directly to the underlying writer. If shouldBuffer is nil,
+// the response will never be buffered and will always be streamed
+// directly to the writer.
//
-// Before calling this function in a middleware handler, make a
-// new buffer or obtain one from a pool (use the sync.Pool) type.
-// Using a pool is generally recommended for performance gains;
-// do profiling to ensure this is the case. If using a pool, be
-// sure to reset the buffer before using it.
+// You can know if shouldBuffer returned true by calling Buffered().
//
-// The returned recorder can be used in place of w when calling
-// the next handler in the chain. When that handler returns, you
-// can read the status code from the recorder's Status() method.
-// The response body fills buf if it was buffered, and the headers
-// are available via w.Header().
-func NewResponseRecorder(w http.ResponseWriter, buf *bytes.Buffer, shouldBuffer func(status int) bool) ResponseRecorder {
+// The provided buffer buf should be obtained from a pool for best
+// performance (see the sync.Pool type).
+//
+// Proper usage of a recorder looks like this:
+//
+// rec := caddyhttp.NewResponseRecorder(w, buf, shouldBuffer)
+// err := next.ServeHTTP(rec, req)
+// if err != nil {
+// return err
+// }
+// if !rec.Buffered() {
+// return nil
+// }
+// // process the buffered response here
+//
+// After a response has been buffered, remember that any upstream header
+// manipulations are only manifest in the recorder's Header(), not the
+// Header() of the underlying ResponseWriter. Thus if you wish to inspect
+// or change response headers, you either need to use rec.Header(), or
+// copy rec.Header() into w.Header() first (see caddyhttp.CopyHeader).
+//
+// Once you are ready to write the response, there are two ways you can do
+// it. The easier way is to have the recorder do it:
+//
+// rec.WriteResponse()
+//
+// This writes the recorded response headers as well as the buffered body.
+// Or, you may wish to do it yourself, especially if you manipulated the
+// buffered body. First you will need to copy the recorded headers, then
+// write the headers with the recorded status code, then write the body
+// (this example writes the recorder's body buffer, but you might have
+// your own body to write instead):
+//
+// caddyhttp.CopyHeader(w.Header(), rec.Header())
+// w.WriteHeader(rec.Status())
+// io.Copy(w, rec.Buffer())
+//
+func NewResponseRecorder(w http.ResponseWriter, buf *bytes.Buffer, shouldBuffer ShouldBufferFunc) ResponseRecorder {
+ // copy the current response header into this buffer so
+ // that any header manipulations on the buffered header
+ // are consistent with what would be written out
+ hdr := make(http.Header)
+ CopyHeader(hdr, w.Header())
return &responseRecorder{
ResponseWriterWrapper: &ResponseWriterWrapper{ResponseWriter: w},
buf: buf,
shouldBuffer: shouldBuffer,
+ header: hdr,
}
}
+func (rr *responseRecorder) Header() http.Header {
+ return rr.header
+}
+
func (rr *responseRecorder) WriteHeader(statusCode int) {
if rr.wroteHeader {
return
@@ -135,9 +173,12 @@ func (rr *responseRecorder) WriteHeader(statusCode int) {
if rr.shouldBuffer == nil {
rr.stream = true
} else {
- rr.stream = !rr.shouldBuffer(rr.statusCode)
+ rr.stream = !rr.shouldBuffer(rr.statusCode, rr.header)
}
+
+ // if not buffered, immediately write header
if rr.stream {
+ CopyHeader(rr.ResponseWriterWrapper.Header(), rr.header)
rr.ResponseWriterWrapper.WriteHeader(rr.statusCode)
}
}
@@ -179,16 +220,32 @@ func (rr *responseRecorder) Buffered() bool {
return !rr.stream
}
+func (rr *responseRecorder) WriteResponse() error {
+ if rr.stream {
+ return nil
+ }
+ CopyHeader(rr.ResponseWriterWrapper.Header(), rr.header)
+ rr.ResponseWriterWrapper.WriteHeader(rr.statusCode)
+ _, err := io.Copy(rr.ResponseWriterWrapper, rr.buf)
+ return err
+}
// ResponseRecorder is a http.ResponseWriter that records
-// responses instead of writing them to the client.
+// responses instead of writing them to the client. See
+// docs for NewResponseRecorder for proper usage.
type ResponseRecorder interface {
HTTPInterfaces
Status() int
Buffer() *bytes.Buffer
Buffered() bool
Size() int
+ WriteResponse() error
}
+// ShouldBufferFunc is a function that returns true if the
+// response should be buffered, given the pending HTTP status
+// code and response headers.
+type ShouldBufferFunc func(status int, header http.Header) bool
+
// Interface guards
var (
_ HTTPInterfaces = (*ResponseWriterWrapper)(nil)
diff --git a/modules/caddyhttp/templates/templates.go b/modules/caddyhttp/templates/templates.go
index 05a2f633a..e9c1da819 100644
--- a/modules/caddyhttp/templates/templates.go
+++ b/modules/caddyhttp/templates/templates.go
@@ -17,7 +17,6 @@ package templates
import (
"bytes"
"fmt"
- "io"
"net/http"
"strconv"
"strings"
@@ -71,8 +70,8 @@ func (t *Templates) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddy
// shouldBuf determines whether to execute templates on this response,
// since generally we will not want to execute for images or CSS, etc.
- shouldBuf := func(status int) bool {
- ct := w.Header().Get("Content-Type")
+ shouldBuf := func(status int, header http.Header) bool {
+ ct := header.Get("Content-Type")
for _, mt := range t.MIMETypes {
if strings.Contains(ct, mt) {
return true
@@ -96,18 +95,17 @@ func (t *Templates) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddy
return err
}
- w.Header().Set("Content-Length", strconv.Itoa(buf.Len()))
- w.Header().Del("Accept-Ranges") // we don't know ranges for dynamically-created content
- w.Header().Del("Last-Modified") // useless for dynamic content since it's always changing
+ rec.Header().Set("Content-Length", strconv.Itoa(buf.Len()))
+ rec.Header().Del("Accept-Ranges") // we don't know ranges for dynamically-created content
+ rec.Header().Del("Last-Modified") // useless for dynamic content since it's always changing
// we don't know a way to guickly generate etag for dynamic content,
// but we can convert this to a weak etag to kind of indicate that
- if etag := w.Header().Get("ETag"); etag != "" {
- w.Header().Set("ETag", "W/"+etag)
+ if etag := rec.Header().Get("Etag"); etag != "" {
+ rec.Header().Set("Etag", "W/"+etag)
}
- w.WriteHeader(rec.Status())
- io.Copy(w, buf)
+ rec.WriteResponse()
return nil
}
diff --git a/modules/caddyhttp/templates/tplcontext.go b/modules/caddyhttp/templates/tplcontext.go
index 5b74623e5..40d137079 100644
--- a/modules/caddyhttp/templates/tplcontext.go
+++ b/modules/caddyhttp/templates/tplcontext.go
@@ -80,7 +80,7 @@ func (c templateContext) Include(filename string, args ...interface{}) (template
// If it is not trusted, be sure to use escaping functions yourself.
func (c templateContext) HTTPInclude(uri string) (template.HTML, error) {
if c.Req.Header.Get(recursionPreventionHeader) == "1" {
- return "", fmt.Errorf("virtual include cycle")
+ return "", fmt.Errorf("virtual request cycle")
}
buf := bufPool.Get().(*bytes.Buffer)